U.S. patent number 11,252,605 [Application Number 16/349,964] was granted by the patent office on 2022-02-15 for method and device for transmitting data unit.
This patent grant is currently assigned to LG ELECTRONICS INC.. The grantee listed for this patent is LG ELECTRONICS INC.. Invention is credited to Sunyoung Lee, Seungjune Yi.
United States Patent |
11,252,605 |
Lee , et al. |
February 15, 2022 |
Method and device for transmitting data unit
Abstract
A transmitting device generates a medium access control (MAC)
protocol data unit (PDU). The transmitting device transmits the MAC
PDU. The MAC PDU includes a MAC control element (CE) start
indicator. The MAC CE start indicator indicates the start point of
the first MAC CE in the MAC PDU.
Inventors: |
Lee; Sunyoung (Seoul,
KR), Yi; Seungjune (Seoul, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
N/A |
KR |
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Assignee: |
LG ELECTRONICS INC. (Seoul,
KR)
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Family
ID: |
62909117 |
Appl.
No.: |
16/349,964 |
Filed: |
January 18, 2018 |
PCT
Filed: |
January 18, 2018 |
PCT No.: |
PCT/KR2018/000838 |
371(c)(1),(2),(4) Date: |
May 14, 2019 |
PCT
Pub. No.: |
WO2018/135874 |
PCT
Pub. Date: |
July 26, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190335361 A1 |
Oct 31, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62447926 |
Jan 19, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
28/06 (20130101); H04W 28/065 (20130101); H04W
80/02 (20130101) |
Current International
Class: |
H04W
28/06 (20090101); H04W 80/02 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
PCT International Application No. PCT/KR2018/000838, Notification
of Transmittal of The International Search Report and the Written
Opinion of the International Searching Authority, or Declaration
dated Apr. 23, 2018, 17 pages. cited by applicant.
|
Primary Examiner: Lee; Jae Y
Assistant Examiner: Guadalupe Cruz; Aixa A
Attorney, Agent or Firm: Lee Hong Degerman Kang Waimey
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the National Stage filing under 35 U.S.C. 371
of International Application No. PCT/KR2018/000838, filed on Jan.
18, 2018, which claims the benefit of U.S. Provisional Application
No. 62/447,926, filed on Jan. 19, 2017, the contents of which are
hereby incorporated by reference herein in its entirety.
Claims
What is claimed is:
1. A method for transmitting, by a transmitting device, a data unit
in a wireless communication system, the method comprising:
generating, by the transmitting device, a medium access control
(MAC) protocol data unit (PDU); and transmitting, by the
transmitting device, the MAC PDU, wherein the MAC PDU includes a
plurality of consecutive MAC sub units, wherein the plurality of
consecutive MAC sub units includes i) zero or more consecutive
first MAC sub units, each consisting of a MAC subheader for a MAC
service data unit (SDU) and the MAC SDU consecutive to the MAC
subheader for the MAC SDU, ii) one or more consecutive second MAC
sub units, each consisting of a MAC subheader for a MAC control
element (CE) and the MAC CE consecutive to the MAC subheader for
the MAC CE, and iii) zero or one third MAC sub unit consisting a
MAC subheader for padding and the padding consecutive to the MAC
subheader for the padding, and wherein the MAC PDU includes a MAC
CE start indicator regarding where a MAC sub unit containing a MAC
CE closest to a beginning of the MAC PDU among the one or more
consecutive second MAC sub units starts in the MAC PDU.
2. The method according to claim 1, wherein the MAC CE start
indicator indicates a sum of a total length of the MAC CEs included
in the MAC PDU and a total length of respective MAC subheaders for
the MAC CEs included in the MAC PDU.
3. The method according to claim 1, wherein the MAC CE start
indicator indicates a sum of a total length of the MAC CEs included
in the MAC PDU, a total length of respective MAC subheaders for the
MAC CEs included in the MAC PDU, a length of padding bits included
in the MAC PDU, and a length of a MAC subheader for the padding
bits included in the MAC PDU.
4. The method according to claim 1, wherein the MAC CE start
indicator indicates a sum of a total length of the MAC SDUs
included in the MAC PDU and a total length of respective MAC
subheaders for the MAC SDUs included in the MAC PDU.
5. The method according to claim 1, wherein the MAC CE start
indicator indicates a sum of a total length of the MAC SDUs
included in the MAC PDU, a total length of respective MAC
subheaders for the MAC SDUs included in the MAC PDU, a length of
padding bits included in the MAC PDU, and a length of a MAC
subheader for the padding bits included in the MAC PDU.
6. The method according to claim 1, wherein the zero or more
consecutive first MAC sub units are placed before the one or more
consecutive second MAC sub units in the MAC PDU.
7. The method according to claim 1, wherein the MAC CE start
indicator is placed in the beginning of the MAC PDU.
8. The method according to claim 1, wherein the MAC PDU includes no
MAC subheader for the MAC CE start indicator.
9. The method according to claim 1, wherein the MAC CE start
indicator is placed in an end of the MAC PDU.
10. A transmitting device for transmitting a data unit in a
wireless communication system, the transmitting device comprising:
a radio frequency (RF) transceiver, and a processor; and a memory
storing at least one program that causes the processor to perform
operations comprising: generating a medium access control (MAC)
protocol data unit (PDU); and transmitting, via the RF transceiver,
the MAC PDU, wherein the MAC PDU includes a plurality of
consecutive MAC sub units, wherein the plurality of consecutive
first MAC sub units includes i) zero or more consecutive MAC sub
units consecutive to the MAC subheader for the MAC SDU, each
consisting of a MAC subheader for a MAC service data unit (SDU) and
the MAC SDU, ii) one or more consecutive second MAC sub units, each
consisting of a MAC subheader for a MAC control element (CE) and
the MAC CE consecutive to the MAC subheader for the MAC CE, and
iii) zero or one third MAC sub unit consisting a MAC subheader for
padding and the padding consecutive to the MAC subheader for the
padding, and wherein the MAC PDU includes a MAC CE start indicator
regarding where a MAC sub unit containing a MAC CE closest to a
beginning of the MAC PDU among the one or more of consecutive
second MAC sub units starts in the MAC PDU.
11. The transmitting device according to claim 10, wherein the MAC
CE start indicator indicates a sum of a total length of the MAC CEs
included in the MAC PDU and a total length of respective MAC
subheaders for the MAC CEs included in the MAC PDU.
12. The transmitting device according to claim 10, wherein the MAC
CE start indicator indicates a sum of a total length of the MAC CEs
included in the MAC PDU, a total length of respective MAC
subheaders for the MAC CEs included in the MAC PDU, a length of
padding bits included in the MAC PDU, and a length of a MAC
subheader for the padding bits included in the MAC PDU.
13. The transmitting device according to claim 10, wherein the MAC
CE start indicator indicates a sum of a total length of the MAC
SDUs included in the MAC PDU and a total length of respective MAC
subheaders for the MAC SDUs included in the MAC PDU.
14. The transmitting device according to claim 10, wherein the MAC
CE start indicator indicates a sum of a total length of the MAC
SDUs included in the MAC PDU, a total length of respective MAC
subheaders for the MAC SDUs included in the MAC PDU, a length of
padding bits included in the MAC PDU, and a length of a MAC
subheader for the padding bits included in the MAC PDU.
15. The transmitting device according to claim 10, wherein the zero
or more consecutive first MAC sub units are placed before the one
or more consecutive second MAC sub units in the MAC PDU.
16. The transmitting device according to claim 10, wherein the MAC
PDU includes no MAC subheader for the MAC CE start indicator.
17. The transmitting device according to claim 10, wherein the MAC
CE start indicator is placed in the beginning of the MAC PDU.
18. The transmitting device according to claim 10, wherein the MAC
CE start indicator is placed in an end of the MAC PDU.
Description
TECHNICAL FIELD
The present invention relates to a wireless communication system,
and more particularly, to a method for transmitting a data unit and
an apparatus therefor.
BACKGROUND ART
As an example of a mobile communication system to which the present
invention is applicable, a 3rd Generation Partnership Project Long
Term Evolution (hereinafter, referred to as LTE) communication
system is described in brief.
FIG. 1 is a view schematically illustrating a network structure of
an E-UMTS as an exemplary radio communication system. An Evolved
Universal Mobile Telecommunications System (E-UMTS) is an advanced
version of a conventional Universal Mobile Telecommunications
System (UMTS) and basic standardization thereof is currently
underway in the 3GPP. E-UMTS may be generally referred to as a Long
Term Evolution (LTE) system. For details of the technical
specifications of the UMTS and E-UMTS, reference can be made to
Release 7 and Release 8 of "3rd Generation Partnership Project;
Technical Specification Group Radio Access Network".
Referring to FIG. 1, the E-UMTS includes a User Equipment (UE),
eNode Bs (eNBs), and an Access Gateway (AG) which is located at an
end of the network (E-UTRAN) and connected to an external network.
The eNBs may simultaneously transmit multiple data streams for a
broadcast service, a multicast service, and/or a unicast
service.
One or more cells may exist per eNB. The cell is set to operate in
one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz and
provides a downlink (DL) or uplink (UL) transmission service to a
plurality of UEs in the bandwidth. Different cells may be set to
provide different bandwidths. The eNB controls data transmission or
reception to and from a plurality of UEs. The eNB transmits DL
scheduling information of DL data to a corresponding UE so as to
inform the UE of a time/frequency domain in which the DL data is
supposed to be transmitted, coding, a data size, and hybrid
automatic repeat and request (HARQ)-related information. In
addition, the eNB transmits UL scheduling information of UL data to
a corresponding UE so as to inform the UE of a time/frequency
domain which may be used by the UE, coding, a data size, and
HARQ-related information. An interface for transmitting user
traffic or control traffic may be used between eNBs. A core network
(CN) may include the AG and a network node or the like for user
registration of UEs. The AG manages the mobility of a UE on a
tracking area (TA) basis. One TA includes a plurality of cells.
Although wireless communication technology has been developed to
LTE based on wideband code division multiple access (WCDMA), the
demands and expectations of users and service providers are on the
rise. In addition, considering other radio access technologies
under development, new technological evolution is required to
secure high competitiveness in the future. Decrease in cost per
bit, increase in service availability, flexible use of frequency
bands, a simplified structure, an open interface, appropriate power
consumption of UEs, and the like are required.
As more and more communication devices demand larger communication
capacity, there is a need for improved mobile broadband
communication compared to existing RAT. Also, massive machine type
communication (MTC), which provides various services by connecting
many devices and objects, is one of the major issues to be
considered in the next generation communication. In addition, a
communication system design considering a service/UE sensitive to
reliability and latency is being discussed. The introduction of
next-generation RAT, which takes into account such advanced mobile
broadband communication, massive MTC (mMCT), and ultra-reliable and
low latency communication (URLLC), is being discussed.
DISCLOSURE
Technical Problem
Due to introduction of new radio communication technology, the
number of user equipments (UEs) to which a BS should provide a
service in a prescribed resource region increases and the amount of
data and control information that the BS should transmit to the UEs
increases. Since the amount of resources available to the BS for
communication with the UE(s) is limited, a new method in which the
BS efficiently receives/transmits uplink/downlink data and/or
uplink/downlink control information using the limited radio
resources is needed.
With development of technologies, overcoming delay or latency has
become an important challenge. Applications whose performance
critically depends on delay/latency are increasing. Accordingly, a
method to reduce delay/latency compared to the legacy system is
demanded.
Also, a method for transmitting/receiving signals effectively in a
system supporting new radio access technology is required.
The technical objects that can be achieved through the present
invention are not limited to what has been particularly described
hereinabove and other technical objects not described herein will
be more clearly understood by persons skilled in the art from the
following detailed description.
Technical Solution
In an aspect of the present invention, provided herein is a method
of transmitting, by a transmitting device, a data unit in a
wireless communication system. The method comprises: generating, by
the transmitting device, a medium access control (MAC) protocol
data unit (PDU); and transmitting, by the transmitting device, the
MAC PDU. The MAC PDU includes a MAC control element (CE) start
indicator. The MAC CE start indicator indicates the start point of
the first MAC CE in the MAC PDU.
In another aspect of the present invention, provided herein is a
transmitting device for transmitting a data unit in a wireless
communication system. The transmitting device comprises: a radio
frequency (RF) unit, and a processor configured to control the RF
unit. The processor may be configured to: generate a medium access
control (MAC) protocol data unit (PDU); and control the RF unit to
transmit the MAC PDU. The MAC PDU includes a MAC control element
(CE) start indicator. The MAC CE start indicator indicates the
start point of the first MAC CE in the MAC PDU.
In each aspect of the present invention, the MAC PDU may always
include the MAC CE start indicator even if there is no MAC CE
included in the MAC PDU.
In each aspect of the present invention, the MAC PDU may include
zero or more MAC service data units (SDUs) and zero or more MAC
CEs.
In each aspect of the present invention, the MAC CE start indicator
may indicate the start point by indicating a sum of a total length
of the MAC CEs included in the MAC PDU and a total length of
respective MAC subheaders for the MAC CEs included in the MAC
PDU.
In each aspect of the present invention, the MAC CE start indicator
may indicate the start point by indicating a sum of a total length
of the MAC CEs included in the MAC PDU, a total length of
respective MAC subheaders for the MAC CEs included in the MAC PDU,
a length of padding bits included in the MAC PDU, and a length of a
MAC subheader for the padding bits included in the MAC PDU.
In each aspect of the present invention, the MAC CE start indicator
may indicate the start point by indicating a sum of a total length
of the MAC SDUs included in the MAC PDU and a total length of
respective MAC subheaders for the MAC SDUs included in the MAC
PDU
In each aspect of the present invention, the MAC CE start indicator
may indicate the start point by indicating a sum of a total length
of the MAC SDUs included in the MAC PDU, a total length of
respective MAC subheaders for the MAC SDUs included in the MAC PDU,
a length of padding bits included in the MAC PDU, and a length of a
MAC subheader for the padding bits included in the MAC PDU.
In each aspect of the present invention, the zero or more MAC SDUs
may be placed before the zero or more MAC CEs in the MAC PDU.
In each aspect of the present invention, the MAC CE start indicator
may be placed in the beginning or end of the MAC PDU.
In each aspect of the present invention, the MAC PDU may include no
MAC subheader for the MAC CE start indicator.
In each aspect of the present invention, the transmitting or
receiving device is an autonomous vehicle that communicates with at
least a mobile terminal, a network, and another autonomous vehicle
other than the device. The above technical solutions are merely
some parts of the embodiments of the present invention and various
embodiments into which the technical features of the present
invention are incorporated can be derived and understood by persons
skilled in the art from the following detailed description of the
present invention.
Advantageous Effects
According to the present invention, radio communication signals can
be efficiently transmitted/received. Therefore, overall throughput
of a radio communication system can be improved.
According to one embodiment of the present invention, a low
cost/complexity UE can perform communication with a base station
(BS) at low cost while maintaining compatibility with a legacy
system.
According to one embodiment of the present invention, the UE can be
implemented at low cost/complexity.
According to one embodiment of the present invention, the UE and
the BS can perform communication with each other at a
narrowband.
According to an embodiment of the present invention, delay/latency
occurring during communication between a user equipment and a BS
may be reduced.
According to the present invention, a transmitting side can process
medium access control (MAC) service data units (SDUs) for
transmission without waiting for the MAC control element (CE)
construction, thereby facilitating the fast MAC PDU processing in
the transmitting side.
According to the present invention, a receiving side can easily
identify a MAC CE in a MAC protocol data unit (PDU), and this will
facilitate the fast MAC CE processing in the receiving side.
Also, signals in a new radio access technology system can be
transmitted/received effectively.
It will be appreciated by persons skilled in the art that the
effects that can be achieved through the present invention are not
limited to what has been particularly described hereinabove and
other advantages of the present invention will be more clearly
understood from the following detailed description.
DESCRIPTION OF DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention, illustrate embodiments of the
invention and together with the description serve to explain the
principle of the invention.
FIG. 1 is a view schematically illustrating a network structure of
an E-UMTS as an exemplary radio communication system.
FIG. 2 is a block diagram illustrating network structure of an
evolved universal mobile telecommunication system (E-UMTS).
FIG. 3 is a block diagram depicting architecture of a typical
E-UTRAN and a typical EPC.
FIG. 4 is a diagram showing a control plane and a user plane of a
radio interface protocol between a UE and an E-UTRAN based on a
3GPP radio access network standard.
FIG. 5 is a view showing an example of a physical channel structure
used in an E-UMTS system.
FIG. 6 is a diagram for medium access control (MAC) structure
overview in a UE side.
FIG. 7 is a diagram for a MAC PDU structure used in the LTE/LTE-A
system.
FIG. 8 are examples of MAC subheaders used in the LTE/LTE-A
system.
FIG. 9 illustrates an overall procedure of the MAC PDU construction
process in the LTE/LTE-A system.
FIG. 10 illustrates examples for a MAC CE start indicator included
in a MAC PDU according to the present invention.
FIG. 11 and FIG. 12 illustrate examples for the order of MAC
subheader(s), MAC SDU(s), MAC CE(s), padding bit(s) and/or MAC CE
LI in a MAC PDU according to the present invention.
FIG. 13 illustrates examples for the order of MAC subheader(s), MAC
SDU(s), MAC CE(s), padding bit(s) and/or MAC CE Pointer in a MAC
PDU according to the present invention.
FIG. 14 is a block diagram illustrating elements of a transmitting
device 100 and a receiving device 200 for implementing the present
invention.
MODE FOR INVENTION
Reference will now be made in detail to the exemplary embodiments
of the present invention, examples of which are illustrated in the
accompanying drawings. The detailed description, which will be
given below with reference to the accompanying drawings, is
intended to explain exemplary embodiments of the present invention,
rather than to show the only embodiments that can be implemented
according to the invention. The following detailed description
includes specific details in order to provide a thorough
understanding of the present invention. However, it will be
apparent to those skilled in the art that the present invention may
be practiced without such specific details.
In some instances, known structures and devices are omitted or are
shown in block diagram form, focusing on important features of the
structures and devices, so as not to obscure the concept of the
present invention. The same reference numbers will be used
throughout this specification to refer to the same or like
parts.
The following techniques, apparatuses, and systems may be applied
to a variety of wireless multiple access systems. Examples of the
multiple access systems include a code division multiple access
(CDMA) system, a frequency division multiple access (FDMA) system,
a time division multiple access (TDMA) system, an orthogonal
frequency division multiple access (OFDMA) system, a single carrier
frequency division multiple access (SC-FDMA) system, and a
multicarrier frequency division multiple access (MC-FDMA) system.
CDMA may be embodied through radio technology such as universal
terrestrial radio access (UTRA) or CDMA2000. TDMA may be embodied
through radio technology such as global system for mobile
communications (GSM), general packet radio service (GPRS), or
enhanced data rates for GSM evolution (EDGE). OFDMA may be embodied
through radio technology such as institute of electrical and
electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),
IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is a part of a
universal mobile telecommunications system (UMTS). 3rd generation
partnership project (3GPP) long term evolution (LTE) is a part of
evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in DL
and SC-FDMA in UL. LTE-advanced (LTE-A) is an evolved version of
3GPP LTE. For convenience of description, it is assumed that the
present invention is applied to 3GPP LTE/LTE-A. However, the
technical features of the present invention are not limited
thereto. For example, although the following detailed description
is given based on a mobile communication system corresponding to a
3GPP LTE/LTE-A system, aspects of the present invention that are
not specific to 3GPP LTE/LTE-A are applicable to other mobile
communication systems.
For example, the present invention is applicable to contention
based communication such as Wi-Fi as well as non-contention based
communication as in the 3GPP LTE/LTE-A system in which an eNB
allocates a DL/UL time/frequency resource to a UE and the UE
receives a DL signal and transmits a UL signal according to
resource allocation of the eNB. In a non-contention based
communication scheme, an access point (AP) or a control node for
controlling the AP allocates a resource for communication between
the UE and the AP, whereas, in a contention based communication
scheme, a communication resource is occupied through contention
between UEs which desire to access the AP. The contention based
communication scheme will now be described in brief. One type of
the contention based communication scheme is carrier sense multiple
access (CSMA). CSMA refers to a probabilistic media access control
(MAC) protocol for confirming, before a node or a communication
device transmits traffic on a shared transmission medium (also
called a shared channel) such as a frequency band, that there is no
other traffic on the same shared transmission medium. In CSMA, a
transmitting device determines whether another transmission is
being performed before attempting to transmit traffic to a
receiving device. In other words, the transmitting device attempts
to detect presence of a carrier from another transmitting device
before attempting to perform transmission. Upon sensing the
carrier, the transmitting device waits for another transmission
device which is performing transmission to finish transmission,
before performing transmission thereof. Consequently, CSMA can be a
communication scheme based on the principle of "sense before
transmit" or "listen before talk". A scheme for avoiding collision
between transmitting devices in the contention based communication
system using CSMA includes carrier sense multiple access with
collision detection (CSMA/CD) and/or carrier sense multiple access
with collision avoidance (CSMA/CA). CSMA/CD is a collision
detection scheme in a wired local area network (LAN) environment.
In CSMA/CD, a personal computer (PC) or a server which desires to
perform communication in an Ethernet environment first confirms
whether communication occurs on a network and, if another device
carries data on the network, the PC or the server waits and then
transmits data. That is, when two or more users (e.g. PCs, UEs,
etc.) simultaneously transmit data, collision occurs between
simultaneous transmission and CSMA/CD is a scheme for flexibly
transmitting data by monitoring collision. A transmitting device
using CSMA/CD adjusts data transmission thereof by sensing data
transmission performed by another device using a specific rule.
CSMA/CA is a MAC protocol specified in IEEE 802.11 standards. A
wireless LAN (WLAN) system conforming to IEEE 802.11 standards does
not use CSMA/CD which has been used in IEEE 802.3 standards and
uses CA, i.e. a collision avoidance scheme. Transmission devices
always sense carrier of a network and, if the network is empty, the
transmission devices wait for determined time according to
locations thereof registered in a list and then transmit data.
Various methods are used to determine priority of the transmission
devices in the list and to reconfigure priority. In a system
according to some versions of IEEE 802.11 standards, collision may
occur and, in this case, a collision sensing procedure is
performed. A transmission device using CSMA/CA avoids collision
between data transmission thereof and data transmission of another
transmission device using a specific rule.
In the present invention, the term "assume" may mean that a subject
to transmit a channel transmits the channel in accordance with the
corresponding "assumption." This may also mean that a subject to
receive the channel receives or decodes the channel in a form
conforming to the "assumption," on the assumption that the channel
has been transmitted according to the "assumption."
In the present invention, a user equipment (UE) may be a fixed or
mobile device. Examples of the UE include various devices that
transmit and receive user data and/or various kinds of control
information to and from a base station (BS). The UE may be referred
to as a terminal equipment (TE), a mobile station (MS), a mobile
terminal (MT), a user terminal (UT), a subscriber station (SS), a
wireless device, a personal digital assistant (PDA), a wireless
modem, a handheld device, etc. In addition, in the present
invention, a BS generally refers to a fixed station that performs
communication with a UE and/or another BS, and exchanges various
kinds of data and control information with the UE and another BS.
The BS may be referred to as an advanced base station (ABS), a
node-B (NB), an evolved node-B (eNB), a base transceiver system
(BTS), an access point (AP), a processing server (PS), etc.
Especially, a BS of the UMTS is referred to as a NB, a BS of the
EPC/LTE is referred to as an eNB, and a BS of the new radio (NR)
system is referred to as a gNB. For convenience of description, in
describing the present invention, a BS will be referred to as an
eNB.
In the present invention, a node refers to a fixed point capable of
transmitting/receiving a radio signal through communication with a
UE. Various types of eNBs may be used as nodes irrespective of the
terms thereof. For example, a BS, a node B (NB), an e-node B (eNB),
a pico-cell eNB (PeNB), a home eNB (HeNB), a relay, a repeater,
etc. may be a node. In addition, the node may not be an eNB. For
example, the node may be a radio remote head (RRH) or a radio
remote unit (RRU). The RRH or RRU generally has a lower power level
than a power level of an eNB. Since the RRH or RRU (hereinafter,
RRH/RRU) is generally connected to the eNB through a dedicated line
such as an optical cable, cooperative communication between RRH/RRU
and the eNB can be smoothly performed in comparison with
cooperative communication between eNBs connected by a radio line.
At least one antenna is installed per node. The antenna may mean a
physical antenna or mean an antenna port or a virtual antenna.
In the present invention, a cell refers to a prescribed
geographical area to which one or more nodes provide a
communication service. Accordingly, in the present invention,
communicating with a specific cell may mean communicating with an
eNB or a node which provides a communication service to the
specific cell. In addition, a DL/UL signal of a specific cell
refers to a DL/UL signal from/to an eNB or a node which provides a
communication service to the specific cell. A node providing UL/DL
communication services to a UE is called a serving node and a cell
to which UL/DL communication services are provided by the serving
node is especially called a serving cell.
Meanwhile, a 3GPP LTE/LTE-A system uses the concept of a cell in
order to manage radio resources and a cell associated with the
radio resources is distinguished from a cell of a geographic
region.
A "cell" of a geographic region may be understood as coverage
within which a node can provide service using a carrier and a
"cell" of a radio resource is associated with bandwidth (BW) which
is a frequency range configured by the carrier. Since DL coverage,
which is a range within which the node is capable of transmitting a
valid signal, and UL coverage, which is a range within which the
node is capable of receiving the valid signal from the UE, depends
upon a carrier carrying the signal, the coverage of the node may be
associated with coverage of the "cell" of a radio resource used by
the node. Accordingly, the term "cell" may be used to indicate
service coverage of the node sometimes, a radio resource at other
times, or a range that a signal using a radio resource can reach
with valid strength at other times.
Meanwhile, the 3GPP LTE-A standard uses the concept of a cell to
manage radio resources. The "cell" associated with the radio
resources is defined by combination of downlink resources and
uplink resources, that is, combination of DL component carrier (CC)
and UL CC. The cell may be configured by downlink resources only,
or may be configured by downlink resources and uplink resources. If
carrier aggregation is supported, linkage between a carrier
frequency of the downlink resources (or DL CC) and a carrier
frequency of the uplink resources (or UL CC) may be indicated by
system information. For example, combination of the DL resources
and the UL resources may be indicated by linkage of system
information block type 2 (SIB2). In this case, the carrier
frequency means a center frequency of each cell or CC. A cell
operating on a primary frequency may be referred to as a primary
cell (Pcell) or PCC, and a cell operating on a secondary frequency
may be referred to as a secondary cell (Scell) or SCC. The carrier
corresponding to the Pcell on downlink will be referred to as a
downlink primary CC (DL PCC), and the carrier corresponding to the
Pcell on uplink will be referred to as an uplink primary CC (UL
PCC). A Scell means a cell that may be configured after completion
of radio resource control (RRC) connection establishment and used
to provide additional radio resources. The Scell may form a set of
serving cells for the UE together with the Pcell in accordance with
capabilities of the UE. The carrier corresponding to the Scell on
the downlink will be referred to as downlink secondary CC (DL SCC),
and the carrier corresponding to the Scell on the uplink will be
referred to as uplink secondary CC (UL SCC). Although the UE is in
RRC-CONNECTED state, if it is not configured by carrier aggregation
or does not support carrier aggregation, a single serving cell
configured by the Pcell only exists.
In the present invention, "PDCCH" refers to a PDCCH, an EPDCCH (in
subframes when configured), a MTC PDCCH (MPDCCH), for an RN with
R-PDCCH configured and not suspended, to the R-PDCCH or, for NB-IoT
to the narrowband PDCCH (NPDCCH).
In the present invention, monitoring a channel implies attempting
to decode the channel. For example, monitoring a PDCCH implies
attempting to decode PDCCH(s) (or PDCCH candidates).
In the present invention, for dual connectivity operation the term
"special Cell" refers to the PCell of the master cell group (MCG)
or the PSCell of the secondary cell group (SCG), otherwise the term
Special Cell refers to the PCell. The MCG is a group of serving
cells associated with a master eNB (MeNB) which terminates at least
S1-MME, and the SCG is a group of serving cells associated with a
secondary eNB (SeNB) that is providing additional radio resources
for the UE but is not the MeNB. The SCG is comprised of a primary
SCell (PSCell) and optionally one or more SCells. In dual
connectivity, two MAC entities are configured in the UE: one for
the MCG and one for the SCG. Each MAC entity is configured by RRC
with a serving cell supporting PUCCH transmission and contention
based Random Access. In this specification, the term SpCell refers
to such cell, whereas the term SCell refers to other serving cells.
The term SpCell either refers to the PCell of the MCG or the PSCell
of the SCG depending on if the MAC entity is associated to the MCG
or the SCG, respectively.
In the present invention, "C-RNTI" refers to a cell RNTI, "SI-RNTI"
refers to a system information RNTI, "P-RNTI" refers to a paging
RNTI, "RA-RNTI" refers to a random access RNTI, "SC-RNTI" refers to
a single cell RNTI'', "SL-RNTI" refers to a sidelink RNTI, and "SPS
C-RNTI" refers to a semi-persistent scheduling C-RNTI.
For terms and technologies which are not specifically described
among the terms of and technologies employed in this specification,
3GPP LTE/LTE-A standard documents, for example, 3GPP TS 36.211,
3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.300, 3GPP TS 36.321,
3GPP TS 36.322, 3GPP TS 36.323 and 3GPP TS 36.331, and 3GPP NR
standard documents, for example, 38.xxx series may be
referenced.
FIG. 2 is a block diagram illustrating network structure of an
evolved universal mobile telecommunication system (E-UMTS). The
E-UMTS may be also referred to as an LTE system. The communication
network is widely deployed to provide a variety of communication
services such as voice (VoIP) through IMS and packet data.
As illustrated in FIG. 2, the E-UMTS network includes an evolved
UMTS terrestrial radio access network (E-UTRAN), an Evolved Packet
Core (EPC) and one or more user equipment. The E-UTRAN may include
one or more evolved NodeB (eNodeB) 20, and a plurality of user
equipment (UE) 10 may be located in one cell. One or more E-UTRAN
mobility management entity (MME)/system architecture evolution
(SAE) gateways 30 may be positioned at the end of the network and
connected to an external network.
As used herein, "downlink" refers to communication from eNB 20 to
UE 10, and "uplink" refers to communication from the UE to an
eNB.
FIG. 3 is a block diagram depicting architecture of a typical
E-UTRAN and a typical EPC.
As illustrated in FIG. 3, an eNB 20 provides end points of a user
plane and a control plane to the UE 10. MME/SAE gateway 30 provides
an end point of a session and mobility management function for UE
10. The eNB and MME/SAE gateway may be connected via an S1
interface.
The eNB 20 is generally a fixed station that communicates with a UE
10, and may also be referred to as a base station (BS) or an access
point. One eNB 20 may be deployed per cell. An interface for
transmitting user traffic or control traffic may be used between
eNBs 20.
The MME provides various functions including NAS signaling to eNBs
20, NAS signaling security, AS Security control, Inter CN node
signaling for mobility between 3GPP access networks, Idle mode UE
Reachability (including control and execution of paging
retransmission), Tracking Area list management (for UE in idle and
active mode), PDN GW and Serving GW selection, MME selection for
handovers with MME change, SGSN selection for handovers to 2G or 3G
3GPP access networks, roaming, authentication, bearer management
functions including dedicated bearer establishment, support for PWS
(which includes ETWS and CMAS) message transmission. The SAE
gateway host provides assorted functions including Per-user based
packet filtering (by e.g. deep packet inspection), Lawful
Interception, UE IP address allocation, Transport level packet
marking in the downlink, UL and DL service level charging, gating
and rate enforcement, DL rate enforcement based on APN-AMBR. For
clarity MME/SAE gateway 30 will be referred to herein simply as a
"gateway," but it is understood that this entity includes both an
MME and an SAE gateway.
A plurality of nodes may be connected between eNB 20 and gateway 30
via the S1 interface. The eNBs 20 may be connected to each other
via an X2 interface and neighboring eNBs may have a meshed network
structure that has the X2 interface.
As illustrated, eNB 20 may perform functions of selection for
gateway 30, routing toward the gateway during a Radio Resource
Control (RRC) activation, scheduling and transmitting of paging
messages, scheduling and transmitting of Broadcast Channel (BCCH)
information, dynamic allocation of resources to UEs 10 in both
uplink and downlink, configuration and provisioning of eNB
measurements, radio bearer control, radio admission control (RAC),
and connection mobility control in LTE_ACTIVE state. In the EPC,
and as noted above, gateway 30 may perform functions of paging
origination, LTE-IDLE state management, ciphering of the user
plane, System Architecture Evolution (SAE) bearer control, and
ciphering and integrity protection of Non-Access Stratum (NAS)
signaling.
The EPC includes a mobility management entity (MME), a
serving-gateway (S-GW), and a packet data network-gateway (PDN-GW).
The MME has information about connections and capabilities of UEs,
mainly for use in managing the mobility of the UEs. The S-GW is a
gateway having the E-UTRAN as an end point, and the PDN-GW is a
gateway having a packet data network (PDN) as an end point.
FIG. 4 is a diagram showing a control plane and a user plane of a
radio interface protocol between a UE and an E-UTRAN based on a
3GPP radio access network standard. The control plane refers to a
path used for transmitting control messages used for managing a
call between the UE and the E-UTRAN. The user plane refers to a
path used for transmitting data generated in an application layer,
e.g., voice data or Internet packet data.
Layer 1 (i.e. L1) of the LTE/LTE-A system is corresponding to a
physical layer. A physical (PHY) layer of a first layer (Layer 1 or
L1) provides an information transfer service to a higher layer
using a physical channel. The PHY layer is connected to a medium
access control (MAC) layer located on the higher layer via a
transport channel. Data is transported between the MAC layer and
the PHY layer via the transport channel. Data is transported
between a physical layer of a transmitting side and a physical
layer of a receiving side via physical channels. The physical
channels use time and frequency as radio resources. In detail, the
physical channel is modulated using an orthogonal frequency
division multiple access (OFDMA) scheme in downlink and is
modulated using a single carrier frequency division multiple access
(SC-FDMA) scheme in uplink.
Layer 2 (i.e. L2) of the LTE/LTE-A system is split into the
following sublayers: Medium Access Control (MAC), Radio Link
Control (RLC) and Packet Data Convergence Protocol (PDCP). The MAC
layer of a second layer (Layer 2 or L2) provides a service to a
radio link control (RLC) layer of a higher layer via a logical
channel. The RLC layer of the second layer supports reliable data
transmission. A function of the RLC layer may be implemented by a
functional block of the MAC layer. A packet data convergence
protocol (PDCP) layer of the second layer performs a header
compression function to reduce unnecessary control information for
efficient transmission of an Internet protocol (IP) packet such as
an IP version 4 (IPv4) packet or an IP version 6 (IPv6) packet in a
radio interface having a relatively small bandwidth.
Layer 3 (i.e. L3) of the LTE/LTE-A system includes the following
sublayers: Radio Resource Control (RRC) and Non Access Stratum
(NAS). A radio resource control (RRC) layer located at the bottom
of a third layer is defined only in the control plane. The RRC
layer controls logical channels, transport channels, and physical
channels in relation to configuration, re-configuration, and
release of radio bearers (RBs). An RB refers to a service that the
second layer provides for data transmission between the UE and the
E-UTRAN. To this end, the RRC layer of the UE and the RRC layer of
the E-UTRAN exchange RRC messages with each other. The non-access
stratum (NAS) layer positioned over the RRC layer performs
functions such as session management and mobility management.
Radio bearers are roughly classified into (user) data radio bearers
(DRBs) and signaling radio bearers (SRBs). SRBs are defined as
radio bearers (RBs) that are used only for the transmission of RRC
and NAS messages.
One cell of the eNB is set to operate in one of bandwidths such as
1.25, 2.5, 5, 10, 15, and 20 MHz and provides a downlink or uplink
transmission service to a plurality of UEs in the bandwidth.
Different cells may be set to provide different bandwidths.
Downlink transport channels for transmission of data from the
E-UTRAN to the UE include a broadcast channel (BCH) for
transmission of system information, a paging channel (PCH) for
transmission of paging messages, and a downlink shared channel
(SCH) for transmission of user traffic or control messages. Traffic
or control messages of a downlink multicast or broadcast service
may be transmitted through the downlink SCH and may also be
transmitted through a separate downlink multicast channel
(MCH).
Uplink transport channels for transmission of data from the UE to
the E-UTRAN include a random access channel (RACH) for transmission
of initial control messages and an uplink SCH for transmission of
user traffic or control messages. Logical channels that are defined
above the transport channels and mapped to the transport channels
include a broadcast control channel (BCCH), a paging control
channel (PCCH), a common control channel (CCCH), a multicast
control channel (MCCH), and a multicast traffic channel (MTCH).
FIG. 5 is a view showing an example of a physical channel structure
used in an E-UMTS system. A physical channel includes several
subframes on a time axis and several subcarriers on a frequency
axis. Here, one subframe includes a plurality of symbols on the
time axis. One subframe includes a plurality of resource blocks and
one resource block includes a plurality of symbols and a plurality
of subcarriers. In addition, each subframe may use certain
subcarriers of certain symbols (e.g., a first symbol) of a subframe
for a physical downlink control channel (PDCCH), that is, an L1/L2
control channel. The PDCCH carries scheduling assignments and other
control information. In FIG. 5, an L1/L2 control information
transmission area (PDCCH) and a data area (PDSCH) are shown. In one
embodiment, a radio frame of 10 ms is used and one radio frame
includes 10 subframes. In addition, one subframe includes two
consecutive slots. The length of one slot may be 0.5 ms. In
addition, one subframe includes a plurality of OFDM symbols and a
portion (e.g., a first symbol) of the plurality of OFDM symbols may
be used for transmitting the L1/L2 control information.
A time interval in which one subframe is transmitted is defined as
a transmission time interval (TTI). Time resources may be
distinguished by a radio frame number (or radio frame index), a
subframe number (or subframe index), a slot number (or slot index),
and the like. TTI refers to an interval during which data may be
scheduled. For example, in the current LTE/LTE-A system, an
opportunity of transmission of an UL grant or a DL grant is present
every 1 ms, and the UL/DL grant opportunity does not exists several
times in less than 1 ms. Therefore, the TTI in the legacy LTE/LTE-A
system is 1 ms.
A base station and a UE mostly transmit/receive data via a PDSCH,
which is a physical channel, using a DL-SCH which is a transmission
channel, except a certain control signal or certain service data.
Information indicating to which UE (one or a plurality of UEs)
PDSCH data is transmitted and how the UE receive and decode PDSCH
data is transmitted in a state of being included in the PDCCH.
For example, in one embodiment, a certain PDCCH is CRC-masked with
a radio network temporary identity (RNTI) "A" and information about
data is transmitted using a radio resource "B" (e.g., a frequency
location) and transmission format information "C" (e.g., a
transmission block size, modulation, coding information or the
like) via a certain subframe. Then, one or more UEs located in a
cell monitor the PDCCH using its RNTI information. And, a specific
UE with RNTI "A" reads the PDCCH and then receive the PDSCH
indicated by B and C in the PDCCH information. In the present
invention, a PDCCH addressed to a certain RNTI means that the PDCCH
is CRC-masked with the certain RNTI. A UE may attempt to decode a
PDCCH using the certain RNTI if the UE is monitoring a PDCCH
addressed to the certain RNTI.
FIG. 6 is a diagram for medium access control (MAC) structure
overview in a UE side.
The MAC layer supports the following functions: mapping between
logical channels and transport channels; multiplexing of MAC SDUs
from one or different logical channels onto transport blocks (TB)
to be delivered to the physical layer on transport channels;
demultiplexing of MAC SDUs from one or different logical channels
from transport blocks (TB) delivered from the physical layer on
transport channels; scheduling information reporting (e.g.
scheduling request, buffer status reporting); error correction
through HARQ; priority handling between UEs by means of dynamic
scheduling; priority handling between logical channels of one MAC
entity; Logical Channel Prioritization (LCP); transport format
selection; and radio resource selection for sidelink (SL).
The MAC provides services to the RLC in the form of logical
channels. A logical channel is defined by the type of information
it carries and is generally classified as a control channel, used
for transmission of control and configuration information necessary
for operating an LTE system, or as a traffic channel, used for the
user data. The set of logical channel types specified for LTE
includes broadcast control channel (BCCH), paging control channel
(PCCH), common control channel (CCCH), dedicated control channel
(DCCH), multicast control channel (MCCH), dedicated traffic channel
(DTCH), multicast traffic channel (MTCH).
From the physical layer, the MAC layer uses services in the form of
transport channels. A transport channel is defined by how and with
what characteristics the information is transmitted over the radio
interface. Data on a transport channel is organized into transport
blocks. In each transmission time interval (TTI), at most one
transport block of dynamic size is transmitted over the radio
interface to/from a terminal in the absence of spatial
multiplexing. In the case of spatial multiplexing (MIMO), there can
be up to two transport blocks per TTI.
Associated with each transport block is a transport format (TF),
specifying how the transport block is to be transmitted over the
radio interface. The transport format includes information about
the transport-block size, the modulation-and-coding scheme, and the
antenna mapping. By varying the transport format, the MAC layer can
thus realize different data rates. Rate control is therefore also
known as transport-format selection.
To support priority handling, multiple logical channels, where each
logical channel has its own RLC entity, can be multiplexed into one
transport channel by the MAC layer. At the receiver, the MAC layer
handles the corresponding demultiplexing and forwards the RLC PDUs
to their respective RLC entity for in-sequence delivery and the
other functions handled by the RLC. To support the demultiplexing
at the receiver, a MAC is used. To each RLC PDU, there is an
associated sub-header in the MAC header. The sub-header contains
the identity of the logical channel (LCID) from which the RLC PDU
originated and the length of the PDU in bytes. There is also a flag
indicating whether this is the last sub-header or not. One or
several RLC PDUs, together with the MAC header and, if necessary,
padding to meet the scheduled transport-block size, form one
transport block which is forwarded to the physical layer.
In addition to multiplexing of different logical channels, the MAC
layer can also insert the so-called MAC control elements into the
transport blocks to be transmitted over the transport channels. A
MAC control element is used for inband control signaling--for
example, timing-advance commands and random-access response.
Control elements are identified with reserved values in the LCID
field, where the LCID value indicates the type of control
information.
Furthermore, the length field in the sub-header is removed for
control elements with a fixed length.
The MAC multiplexing functionality is also responsible for handling
of multiple component carriers in the case of carrier aggregation.
The basic principle for carrier aggregation is independent
processing of the component carriers in the physical layer,
including control signaling, scheduling and hybrid-ARQ
retransmissions, while carrier aggregation is invisible to RLC and
PDCP. Carrier aggregation is therefore mainly seen in the MAC
layer, where logical channels, including any MAC control elements,
are multiplexed to form one (two in the case of spatial
multiplexing) transport block(s) per component carrier with each
component carrier having its own hybrid-ARQ entity.
FIG. 7 is a diagram for a MAC PDU structure used in the LTE/LTE-A
system. FIG. 8 are examples of MAC subheaders used in the LTE/LTE-A
system.
A MAC PDU is a bit string that is byte aligned (i.e. multiple of 8
bits) in length. In FIG. 8, bit strings are represented by tables
in which the most significant bit is the leftmost bit of the first
line of the table, the least significant bit is the rightmost bit
on the last line of the table, and more generally the bit string is
to be read from left to right and then in the reading order of the
lines. The bit order of each parameter field within a MAC PDU is
represented with the first and most significant bit in the leftmost
bit and the last and least significant bit in the rightmost
bit.
MAC SDUs are bit strings that are byte aligned (i.e. multiple of 8
bits) in length. An SDU is included into a MAC PDU from the first
bit onward. The MAC entity shall ignore the value of reserved bits
in downlink MAC PDUs.
A MAC PDU consists of a MAC header, zero or more MAC service data
units (MAC SDUs), zero, or more MAC control elements (MAC CEs), and
optionally padding, as described in FIG. 7. Both the MAC header and
the MAC SDUs are of variable sizes.
A MAC PDU header consists of one or more MAC PDU subheaders; each
subheader corresponds to either a MAC SDU, a MAC control element or
padding. Referring to FIG. 8, a MAC PDU subheader consists of the
five or six header fields R/F2/E/LCID/(F)/L but for the last
subheader in the MAC PDU and for fixed sized MAC control elements.
The last subheader in the MAC PDU and subheaders for fixed sized
MAC control elements consist solely of the four header fields
R/F2/E/LCID. A MAC PDU subheader corresponding to padding consists
of the four header fields R/F2/E/LCID.
In the LTE/LTE-A system, MAC PDU subheaders have the same order as
the corresponding MAC SDUs, MAC control elements and padding. In
the LTE/LTE-A system, MAC control elements are always placed before
any MAC SDU.
Padding occurs at the end of the MAC PDU, except when single-byte
or two-byte padding is required. Padding may have any value and the
MAC entity shall ignore it. When padding is performed at the end of
the MAC PDU, zero or more padding bytes are allowed. In the
LTE/LTE-A system, when single-byte or two-byte padding is required,
one or two MAC PDU subheaders corresponding to padding are placed
at the beginning of the MAC PDU before any other MAC PDU subheader.
A maximum of one MAC PDU can be transmitted per TB per MAC entity.
A maximum of one MCH MAC PDU can be transmitted per TTI.
A fully mobile and connected society is expected in the near
future, which will be characterized by a tremendous amount of
growth in connectivity, traffic volume and a much broader range of
usage scenarios. Some typical trends include explosive growth of
data traffic, great increase of connected devices and continuous
emergence of new services. Besides the market requirements, the
mobile communication society itself also requires a sustainable
development of the eco-system, which produces the needs to further
improve system efficiencies, such as spectrum efficiency, energy
efficiency, operational efficiency and cost efficiency. To meet the
above ever-increasing requirements from market and mobile
communication society, next generation access technologies are
expected to emerge in the near future.
Work has started in ITU and 3GPP to develop requirements and
specifications for new radio systems, as in the Recommendation
ITU-R M.2083 "Framework and overall objectives of the future
development of IMT for 2020 and beyond", as well as 3GPP SA1 study
item New Services and Markets Technology Enablers (SMARTER) and SA2
study item Architecture for the new RAT (NR) System (also referred
to as 5G new RAT). It is required to identify and develop the
technology components needed for successfully standardizing the NR
system timely satisfying both the urgent market needs, and the more
long-term requirements set forth by the ITU-R IMT-2020 process. In
order to achieve this, evolutions of the radio interface as well as
radio network architecture have to be considered in the "New Radio
Access Technology."
FIG. 9 illustrates an overall procedure of the MAC PDU construction
process in the LTE/LTE-A system.
In the LTE/LTE-A system, a MAC PDU construction process at a UE
starts when a UL grant is received, as follows.
>1. The UE receives a UL grant from an eNB.
>2. The MAC entity performs Logical Channel Prioritization (LCP)
procedure to determine the RLC PDU size for each RLC entity.
>3. The MAC entity indicates the determined RLC PDU size to each
RLC entity.
>4. Each RLC entity performs segmentation and/or concatenation
of RLC SDUs to construct a RLC PDU. For each RLC PDU, Framing Info
(FI) and RLC Sequence Number (RSN) are mandatorily present. The
Length Indicator (LI) is included each time two RLC SDUs (segments)
are concatenated.
>5. Each RLC entity delivers the constructed RLC PDU to the MAC
entity.
>6. The MAC entity concatenates RLC PDUs received from multiple
RLC entities.
>7. The MAC entity sets the value of MAC subheader for each MAC
SDU, and collects all MAC subheaders in front of the MAC PDU to
form a MAC header.
The MAC PDU construction process in the LTE/LTE-A system has the
following problems and/or redundancies. A UE can start the MAC PDU
construction process only after the UE receives a UL grant.
Especially, RLC segmentation and concatenation process starts only
after the MAC entity indicates the RLC PDU size to the RLC entity,
which takes long time before MAC PDU construction. Due to the
variable length nature of MAC SDU and MAC subheaders, determining a
RLC PDU size for each RLC entity is very complex. In the meantime,
in the LTE/LTE-A system, a PDCP SN is already included in a RLC
SDU, and adding another SN in the RLC is redundant. The same
function is spread over two layers (MAC and RLC), which is
redundant and inefficient, since the RLC includes a LI field to
indicate the length of RLC SDU (segment), and the MAC includes a L
field to indicate the length of MAC SDU.
Besides, in the LTE/LTE-A system, MAC control elements are always
placed before any MAC SDU. A MAC PDU cannot be delivered to the PHY
until whole the MAC PDU is constructed, because all the MAC
subheaders should be collected together and put into the front of
the MAC PDU.
During the 3GPP meetings for the NR system, with a purpose of
enabling fast delivery of MAC PDU to PHY layer, it was agreed that
MAC sub-headers are interleaved with MAC SDUs such that a MAC
subheader is placed before its corresponding MAC SDU or MAC CE.
With interleaved MAC sub-header, it is expected that MAC can
deliver the generated part of MAC PDU immediately after attaching a
MAC subheader to a corresponding generated MAC SDU or MAC CE, even
before generating whole MAC PDU, so that the PHY can start
processing of the received part of MAC PDU quickly.
For the same purpose of enabling fast delivery of MAC PDU to PHY
layer, it was proposed not to allow place MAC CEs in the middle of
the MAC PDU. In a UE, some MAC CEs such as BSR or PHR need to
reflect the latest UE status before transmission. For example, BSR
MAC CE is placed at the beginning of MAC PDU as in the LTE/LTE-A
system, the MAC at the UE can only deliver the MAC PDU after a
complete MAC PDU is generated, because a BSR MAC can only be
generated after placing all MAC SDUs, and the PHY needs to receive
MAC PDU in order, i.e., from the beginning part, for the PHY layer
processing. Placing the MAC CE at the end of a MAC PDU enables
partial MAC PDU delivery to physical layer while gives more time to
reflect the latest UE status in the MAC CE. In the receiving side,
the placement of MAC CEs does not affect receiving process as the
receiving process would start only after receiving a whole
transport block. In the receiving side, especially if the receiving
side is a scheduler, what is important is how fast the receiver
identifies the placement of MAC CEs. It is because the receiving
side could identify MAC CEs at the end of the MAD PDU even before
receiving a whole transport block and perform scheduling fast based
on the MAC CEs if the MAC CEs are not placed in the middle of the
MAC PDU but placed at the end of the MAC CE. However, there are
following problems at this proposal.
With the interleaved MAC subheader, which is placed before its
corresponding MAC SDU or MAC CE, decoding of the MAC CEs which is
placed at the end of MAC PDU is impossible because the receiving
side doesn't know how many MAC SDUs are placed in front of MAC CE,
i.e., the starting point of MAC CE within the MAC PDU. In other
words, if a MAC subheader is attached at the beginning of a
corresponding MAC SDU or MAC CE, the BS has to process all MAC
SDU(s) before identifying the MAC CE(s). This burden is definitely
not preferred in the BS side. Therefore, in order to benefit from
MAC CE(s) placed at the end of a MAC PDU with interleaved MAC
sub-header(s), a new method is needed to indicate the starting
point of the MAC CE(s) within the MAC PDU.
For the convenience for the description, in the following
description, the present invention is described using an example
where a UE is a transmitting side and a BS or network is a
receiving side, but the present invention is also applied in the
same or similar manner even when a BS or network is a transmitting
side and a UE is a receiving side, except that a UE should receive
a UL grant used for MAC PDU transmission while a BS does not have
to receive a DL grant used for MAC PDU transmission but can
allocate it for itself.
As a solution for the above-mentioned problems, the present
invention proposes that a MAC PDU include a MAC CE start indicator
indicating where the first MAC CE (i.e. the leftmost MAC CE) starts
in the MAC PDU. In an example of the present invention, the MAC CE
start indicator may be an indicator, i.e., MAC Control Elements
Length Indicator (MAC CE LI), indicating a total length of MAC
Control Elements (CEs) included in the MAC PDU, as described in
Example 1 below. In an alternative example of the present
invention, the MAC CE start indicator may be an indicator, i.e.,
MAC CE pointer, indicating a starting point of the first MAC CE
included in the MAC PDU, as described in Example 2 below. In other
words, the MAC CE start indicator of the present invention may be
implemented with a MAC CE LI or MAC CE pointer.
As another solution which can be applied alone, or applied together
with the MAC CE start indicator, the present invention proposes
attaching a MAC subheader at the end of a corresponding MAC SDU or
MAC CE. In this solution, a MAC at a receiving side can process the
MAC PDU from the end of the MAC PDU to obtain MAC CE(s) and then
process the remaining part of the MAC PDU to obtain MAC SDU(s).
FIG. 10 illustrates examples for a MAC CE start indicator included
in a MAC PDU according to the present invention.
Referring to FIG. 10. the MAC CE start indicator, which is notated
with "X" in FIG. 10, at the start or end of a MAC PDU may indicate
a total length of MAC CEs included in the MAC PDU. The MAC CE start
indicator, which is notated with "Y" in FIG. 10, at the start or
end of a MAC PDU may indicate a starting point of the first MAC CE
included in the MAC PDU.
FIG. 10(a) and FIG. 10(b) are different in that each MAC subheader
of FIG. 10(a) exists immediately before a corresponding MAC SDU or
MAC CE whereas each MAC subheader of FIG. 10(b) exists immediately
after a corresponding MAC SDU or MAC CE. The present invention can
be applied to a MAC PDU with interleaved MAC subheader(s), each of
which is placed before a corresponding MAC SDU or MAC CE, and a MAC
PDU with interleaved MAC subheader(s), each of which is placed
after a corresponding MAC SDU or MAC CE.
Example 1
MAC CEs Length Indicator (MAC CE LI)
When a UE generates a MAC PDU, the UE includes a MAC CE LI
indicating a total length of MAC CE(s) in the MAC PDU. The total
length of MAC CE(s) is calculated as the sum of the length of all
MAC CEs and the length of all MAC subheaders corresponding to each
of the MAC CEs, which are included in the MAC PDU. In the present
invention, a UE may generate a MAC PDU as follows.
A UE receives an uplink grant from a network. The UE determines,
e.g., as a result of logical channel prioritization procedure, that
zero or more MAC SDUs and/or zero or more MAC CEs are to be
included in a MAC PDU which is to be transmitted by using the
uplink grant. The UE generates a MAC subheader corresponding to
each of MAC SDUs and/or MAC CEs. The UE generates a MAC CE LI
indicating the total length of MAC CEs included in the MAC PDU as
follows. The UE calculates the total length of MAC CEs as a sum of
length of all MAC CEs and length of all MAC subheaders
corresponding to MAC CEs included in the MAC PDU. The UE doesn't
not count the length of any MAC SDU or the length of any MAC
subheader corresponding to MAC SDU included in the MAC PDU. The UE
may additionally count the length of padding bits and the length of
MAC subheader corresponding to padding bits included in the MAC
PDU. The UE sets a field of the MAC CE LI to the calculated total
length of MAC CEs.
The MAC CE LI can be of fixed size, e.g., 1 byte. The MAC CE LI may
be always included in the MAC PDU although there is no MAC CE
included in the MAC PDU. The MAC CE LI may additionally indicate
whether there is no MAC CE included in the MAC PDU or not, by
including a field in the MAC CE LI. For example, the field is set
to a value, e.g., 1, if there is at least one MAC CE in the MAC
PDU. Otherwise, the field is set to, e.g., 0, if there is no MAC CE
in the MAC PDU. If the field of the MAC CE LI indicates that there
is no MAC CE included in the MAC PDU, the MAC CE LI may not include
a field indicating the total length of MAC CE(s) included in the
MAC PDU. In other words, if the field of the MAC CE LI indicates
that there is no MAC CE included in the MAC PDU, a field indicating
the total length of MAC CE included in the MAC PDU may be omitted
in the MAC CE LI.
When the UE generates the MAC PDU including the MAC subheaders, the
MAC SDUs, the MAC CEs, padding bits, and/or the MAC CE LI, the UE
places the MAC CE LI as follows. The MAC CE LI is placed at the end
of the MAC PDU, i.e., the rightmost position of the MAC PDU. For
example, the MAC CE LI is placed after all MAC SDUs, all MAC CEs,
padding bits, and all MAC subheaders corresponding to the MAC
SDU/CE or padding bits. For another example, the MAC CE LI is
placed after all MAC SDUs, all MAC CEs, and all MAC subheaders
corresponding to MAC SDUs/CEs. Alternatively, the MAC CE LI is
placed in the beginning of the MAC PDU, i.e., the leftmost position
of the MAC PDU. For example, the MAC CE LI is placed before any MAC
SDU, any MAC CE, any padding bits, and any MAC subheader
corresponding to the MAC SDU/CE or padding bits.
FIG. 11 and FIG. 12 illustrate examples for the order of MAC
subheader(s), MAC SDU(s), MAC CE(s), padding bit(s) and/or MAC CE
LI in a MAC PDU according to the present invention. FIG. 11
illustrates examples for MAC payload placement order for a MAC PDU
with interleaved MAC subheader(s), each of which is placed before a
corresponding MAC SDU or MAC CE. FIG. 12 illustrates examples for
MAC payload placement order for a MAC PDU with interleaved MAC
subheader(s), each of which is placed after a corresponding MAC SDU
or MAC CE. FIG. 12(a), FIG. 12(b), FIG. 12(c) and FIG. 12(d) are
substantially the same as FIG. 11(a), FIG. 11(b), FIG. 11(c) and
FIG. 11(d), except for the location of MAC subheaders.
MAC subheader(s), MAC SDU(s), MAC CE(s), padding bit(s), and/or MAC
CE LI may be placed within a MAC PDU, in the order illustrated in
FIG. 11(a), FIG. 11(b), FIG. 11(c), or FIG. 11(d). In FIG. 11, a
MAC PDU has each MAC subheader immediately before a corresponding
MAC SDU, MAC CE or padding.
Referring to FIG. 11(a), a MAC PDU may include MAC payload in the
following order: `MAC subheader+MAC SDU`, `MAC subheader+padding
bits` and/or `MAC subheader+MAC CE`, and `MAC CE LI`. In the
payload placement order illustrated in FIG. 11(a), a total length
of MAC CEs is calculated as a sum of length of all MAC CEs and all
MAC subheaders for the MAC CEs.
Referring to FIG. 11(b), a MAC PDU may include MAC payload in the
following order: `MAC subheader+MAC SDU`, `MAC subheader+MAC CE`
and/or `MAC subheader+padding bits`, and MAC CE LI. In the payload
placement order illustrated in FIG. 11(b), a total length of MAC
CEs is calculated as a sum of length of all MAC CEs, padding bits,
and all MAC subheaders for the MAC CEs and padding.
Referring to FIG. 11(c), a MAC PDU may include MAC payload in the
following order: MAC CE LI and, `MAC subheader+MAC SDU`, `MAC
subheader+padding bits`, and/or `MAC subheader+MAC CE`. In the
payload placement order illustrated in FIG. 11(c), a total length
of MAC CEs is calculated as a sum of length of all MAC CEs and all
MAC subheaders for the MAC CEs.
Referring to FIG. 11(d), a MAC PDU may include MAC payload in the
following order: MAC CE LI and, `MAC subheader+MAC SDU`, `MAC
subheader+padding bits`, and/or `MAC subheader+MAC CE`. In the
payload placement order illustrated in FIG. 11(d), a total length
of MAC CEs is calculated as a sum of length of all MAC CEs, padding
bits, and all MAC subheaders for the MAC CEs and padding.
MAC subheader(s), MAC SDU(s), MAC CE(s), padding bit(s), and/or MAC
CE LI can be placed within a MAC PDU, in the order illustrated in
FIG. 12(a), FIG. 12(b), FIG. 12(c), or FIG. 12(d). In FIG. 12, a
MAC PDU has each MAC subheader immediately after a corresponding
MAC SDU, MAC CE or padding.
Referring to FIG. 12(a), a MAC PDU may include MAC payload in the
following order: `MAC SDU+MAC subheader`, `padding bits+MAC
subheader` and/or `MAC CE+MAC subheader`, and `MAC CE LI`. In the
payload placement order illustrated in FIG. 12(a), a total length
of MAC CEs is calculated as a sum of length of all MAC CEs and all
MAC subheaders for the MAC CEs.
Referring to FIG. 12(b), a MAC PDU may include MAC payload in the
following order: `MAC SDU+MAC subheader`, `MAC CE+MAC subheader`
and/or `padding bits+MAC subheader`, and MAC CE LI. In the payload
placement order illustrated in FIG. 12(b), a total length of MAC
CEs is calculated as a sum of length of all MAC CEs, padding bits,
and all MAC subheaders for the MAC CEs and padding.
Referring to FIG. 12(c), a MAC PDU may include MAC payload in the
following order: MAC CE LI and, `MAC SDU+MAC subheader`, `padding
bits+MAC subheader`, and/or `MAC CE+MAC subheader`. In the payload
placement order illustrated in FIG. 12(c), a total length of MAC
CEs is calculated as a sum of length of all MAC CEs and all MAC
subheaders for the MAC CEs.
Referring to FIG. 12(d), a MAC PDU may include MAC payload in the
following order: MAC CE LI and, `MAC SDU+MAC subheader`, `padding
bits+MAC subheader`, and/or `MAC CE+MAC subheader`. In the payload
placement order illustrated in FIG. 12(d), a total length of MAC
CEs is calculated as a sum of length of all MAC CEs, padding bits,
and all MAC subheaders for the MAC CEs and padding.
In the present invention, the MAC CE LI can be a MAC CE or MAC
subheader. In other words, the MAC CE LI can be included in a MAC
PDU in the form of a MAC CE or MAC subheader.
The MAC CE LI may not be identified by any MAC subheader. In other
words, the payload for the MAC CE LI may not have any corresponding
MAC subheader.
When the network receives the MAC PDU including the MAC CE LI, the
network finds the location of MAC CEs in the MAC PDU by counting
the total length of MAC CEs from the end of the MAC PDU. For
example, if the MAC CE LI is placed at the end of the MAC PDU, the
UE considers that MAC CEs are placed in the MAC PDU with the length
indicated by the MAC CE LI from the end point of the MAC PDU except
for the MAC CE LI. In other words, the network considers that MAC
CEs are included in the MAC PDU with an offset which is equal to
whole MAC PDU size minus total length of MAC CEs from the beginning
of the MAC PDU. After the network finds the location of MAC CEs,
i.e., the network finds where the MAC CEs are placed in the MAC
PDU, the network may process the MAC CEs prior to processing MAC
SDU(s) even though the MAC CEs are placed after the MAC SDU(s).
Example 2
MAC CE Pointer
When a UE generates a MAC PDU, the UE includes a MAC CE Pointer
indicating an offset value between the beginning point of the MAC
PDU and the starting point of the first MAC CE in the MAC PDU. If
the MAC CE Pointer is placed in the beginning of the MAC PDU, the
MAC CE Pointer indicating the offset value between the beginning
point of the MAC PDU except for the MAC CE Pointer and the starting
point of the first MAC CE in the MAC PDU. In the present invention,
a UE may generate a MAC PDU as follows.
A UE receives an uplink grant from a network. The UE determines,
e.g., as a result of a logical channel prioritization procedure,
that zero or more MAC SDUs and/or zero or more MAC CEs are to be
included in a MAC PDU which is to be transmitted by using the
uplink grant. The UE generates a MAC subheader corresponding to
each of MAC SDUs and/or MAC CEs. The UE generates a MAC CE Pointer
indicating the offset value as follows. The UE calculates the
offset value as a sum of length of all MAC SDUs and length of all
MAC subheaders corresponding to MAC SDUs included in the MAC PDU.
The UE doesn't not count the length of any MAC CE or the length of
any MAC subheader corresponding to MAC CE included in the MAC PDU.
The UE may additionally count the length of padding bits and the
length of MAC subheader corresponding to padding bits included in
the MAC PDU. The UE sets a field of the MAC CE Pointer to the
calculated offset value.
The MAC CE Pointer can be of fixed size, e.g., 1 byte;
The MAC CE Pointer may be always included in the MAC PDU although
there is no MAC CE included in the MAC PDU. The MAC CE Pointer may
additionally indicate whether there is no MAC CE included in the
MAC PDU or not, by including a field in the MAC CE Pointer. For
example, the field is set to a value, e.g., 1, if there is at least
one MAC CE in the MAC PDU. Otherwise, the field is set to, e.g., 0,
if there is no MAC CE in the MAC PDU. If the field of the MAC CE
Pointer indicates that there is no MAC CE included in the MAC PDU,
the MAC CE Pointer may not include a field indicating the offset
value included in the MAC PDU. In other words, if the field of the
MAC CE Pointer indicates that there is no MAC CE included in the
MAC PDU, a field indicating the offset value may be omitted in the
MAC CE Pointer.
When the UE generates the MAC PDU including the MAC subheaders, the
MAC SDUs, the MAC CEs, padding bits, and/or the MAC CE Pointer, the
UE places the MAC CE Pointer as follows. The MAC CE Pointer is
placed in the beginning of the MAC PDU, i.e., the leftmost position
of the MAC PDU. For example, the MAC CE Pointer is placed before
any MAC SDU, any MAC CE, any padding bits, and any MAC subheader
corresponding to the MAC SDU/CE or padding bits. Alternatively, the
MAC CE Pointer is placed at the end of the MAC PDU, i.e., the
rightmost position of the MAC PDU. For example, the MAC CE Pointer
is placed after all MAC SDUs, all MAC CEs, padding bits, and all
MAC subheaders corresponding to the MAC SDUs/CEs or padding bits.
For another example, the MAC CE Pointer is placed after all MAC
SDUs, all MAC CEs, and all MAC subheaders corresponding to the MAC
SDUs/CEs.
FIG. 13 illustrates examples for the order of MAC subheader(s), MAC
SDU(s), MAC CE(s), padding bit(s) and/or MAC CE Pointer in a MAC
PDU according to the present invention.
MAC subheader(s), MAC SDU(s), MAC CE(s), padding bit(s), and/or MAC
CE Pointer may be placed within a MAC PDU, in the order illustrated
in FIG. 13(a), FIG. 13(b), FIG. 13(c), or FIG. 13(d). Although FIG.
13 shows examples for a MAC PDU having each MAC subheader
immediately before a corresponding MAC SDU, MAC CE or padding, the
same payload placement order is applied to a MAC PDU having each
MAC subheader immediately after a corresponding MAC SDU, MAC CE or
padding, except for the location of MAC subheaders.
Referring to FIG. 13(a), a MAC PDU may include MAC payload in the
following order: MAC CE Pointer and, `MAC subheader+MAC SDU`, `MAC
subheader+MAC CE` and/or `MAC subheader+padding bits`. In the
payload placement order illustrated in FIG. 13(a), the offset value
is calculated as a sum of length of all MAC SDUs and all MAC
subheaders for MAC SDUs.
Referring to FIG. 13(b), a MAC PDU may include MAC payload in the
following order: MAC CE Pointer and, `MAC subheader+MAC SDU`, `MAC
subheader+padding bits`, `MAC subheader+MAC CE`. In the payload
placement order illustrated in FIG. 13(b), a MAC CE Pointer is
calculated as a sum of length of all MAC SDUs, length of padding
bits, and all MAC subheaders for the MAC SDUs and padding.
Referring to FIG. 13(c), a MAC PDU may include MAC payload in the
following order: `MAC subheader+MAC SDU`, `MAC subheader+padding
bits` and/or `MAC subheader+MAC CE`, and MAC CE Pointer. In the
payload placement order illustrated in FIG. 13(c), the offset value
is calculated as a sum of length of all MAC SDUs and all MAC
subheaders for the MAC SDUs.
Referring to FIG. 13(d), a MAC PDU may include MAC payload in the
following order: `MAC subheader/MAC SDU`, `MAC subheader/MAC CE`
and/or `MAC subheader+padding bits`, and MAC CE Pointer. orIn the
payload placement order illustrated in FIG. 13(d), the offset value
is calculated as a sum of length of all MAC SDUs, padding bits, and
all MAC subheaders for the MAC SDUs and padding.
The MAC CE Pointer can be a MAC CE or a MAC subheader. In other
words, the MAC CE Pointer can be included in a MAC PDU in the form
of a MAC CE or MAC subheader.
The MAC CE Pointer may not be identified by any MAC subheader. In
other words, the payload for the MAC CE LI may not have any
corresponding MAC subheader.
When the network receives the MAC PDU including the MAC CE Pointer,
the network finds the location of MAC CEs in the MAC PDU by
counting the offset value from the beginning of the MAC PDU. For
example, if MAC CE Pointer is placed in the beginning of the MAC
PDU, the UE considers that MAC CEs are placed in the MAC PDU with
an offset value indicated by the MAC CE Pointer from the beginning
point of the MAC PDU except for the MAC CE Pointer. After the
network finds the location of MAC CEs, i.e., the network finds
where the MAC CEs are placed in the MAC PDU, the network may
process the MAC CEs prior to processing MAC SDU(s) even though the
MAC CEs are placed after the MAC SDU(s).
As mentioned before, the present invention has following benefits.
The transmitting side (e.g. UE) can process MAC SDUs for
transmission without waiting for the MAC CE construction, and this
will facilitate the fast MAC PDU processing in the transmitting
side. A receiving side (e.g. BS) can easily identify a MAC CE by
processing a MAC PDU based on the MAC CE start indicator, and this
will facilitate the fast MAC CE processing in the receiving
side.
The present invention also applies to DL data transmission where
the transmitting side is a BS and the receiving side is a UE.
FIG. 14 is a block diagram illustrating elements of a transmitting
device 100 and a receiving device 200 for implementing the present
invention.
The transmitting device 100 and the receiving device 200
respectively include Radio Frequency (RF) units 13 and 23 capable
of transmitting and receiving radio signals carrying information,
data, signals, and/or messages, memories 12 and 22 for storing
information related to communication in a wireless communication
system, and processors 11 and 21 operationally connected to
elements such as the RF units 13 and 23 and the memories 12 and 22
to control the elements and configured to control the memories 12
and 22 and/or the RF units 13 and 23 so that a corresponding device
may perform at least one of the above-described embodiments of the
present invention.
The memories 12 and 22 may store programs for processing and
controlling the processors 11 and 21 and may temporarily store
input/output information. The memories 12 and 22 may be used as
buffers.
The processors 11 and 21 generally control the overall operation of
various modules in the transmitting device and the receiving
device. Especially, the processors 11 and 21 may perform various
control functions to implement the present invention. The
processors 11 and 21 may be referred to as controllers,
microcontrollers, microprocessors, or microcomputers. The
processors 11 and 21 may be implemented by hardware, firmware,
software, or a combination thereof. In a hardware configuration,
application specific integrated circuits (ASICs), digital signal
processors (DSPs), digital signal processing devices (DSPDs),
programmable logic devices (PLDs), or field programmable gate
arrays (FPGAs) may be included in the processors 11 and 21.
Meanwhile, if the present invention is implemented using firmware
or software, the firmware or software may be configured to include
modules, procedures, functions, etc. performing the functions or
operations of the present invention. Firmware or software
configured to perform the present invention may be included in the
processors 11 and 21 or stored in the memories 12 and 22 so as to
be driven by the processors 11 and 21.
The processor 11 of the transmitting device 100 performs
predetermined coding and modulation for a signal and/or data
scheduled to be transmitted to the outside by the processor 11 or a
scheduler connected with the processor 11, and then transfers the
coded and modulated data to the RF unit 13. For example, the
processor 11 converts a data stream to be transmitted into K layers
through demultiplexing, channel coding, scrambling, and modulation.
The coded data stream is also referred to as a codeword and is
equivalent to a transport block which is a data block provided by a
MAC layer. One transport block (TB) is coded into one codeword and
each codeword is transmitted to the receiving device in the form of
one or more layers. For frequency up-conversion, the RF unit 13 may
include an oscillator. The RF unit 13 may include N.sub.t (where
N.sub.t is a positive integer) transmit antennas.
A signal processing process of the receiving device 200 is the
reverse of the signal processing process of the transmitting device
100. Under control of the processor 21, the RF unit 23 of the
receiving device 200 receives radio signals transmitted by the
transmitting device 100. The RF unit 23 may include N.sub.r (where
N.sub.r is a positive integer) receive antennas and frequency
down-converts each signal received through receive antennas into a
baseband signal. The processor 21 decodes and demodulates the radio
signals received through the receive antennas and restores data
that the transmitting device 100 intended to transmit.
The RF units 13 and 23 include one or more antennas. An antenna
performs a function for transmitting signals processed by the RF
units 13 and 23 to the exterior or receiving radio signals from the
exterior to transfer the radio signals to the RF units 13 and 23.
The antenna may also be called an antenna port. Each antenna may
correspond to one physical antenna or may be configured by a
combination of more than one physical antenna element. The signal
transmitted from each antenna cannot be further deconstructed by
the receiving device 200. An RS transmitted through a corresponding
antenna defines an antenna from the view point of the receiving
device 200 and enables the receiving device 200 to derive channel
estimation for the antenna, irrespective of whether the channel
represents a single radio channel from one physical antenna or a
composite channel from a plurality of physical antenna elements
including the antenna. That is, an antenna is defined such that a
channel carrying a symbol of the antenna can be obtained from a
channel carrying another symbol of the same antenna. An RF unit
supporting a MIMO function of transmitting and receiving data using
a plurality of antennas may be connected to two or more
antennas.
In the embodiments of the present invention, a UE operates as the
transmitting device 100 in UL and as the receiving device 200 in
DL. In the embodiments of the present invention, an eNB operates as
the receiving device 200 in UL and as the transmitting device 100
in DL. Hereinafter, a processor, an RF unit, and a memory included
in the UE will be referred to as a UE processor, a UE RF unit, and
a UE memory, respectively, and a processor, an RF unit, and a
memory included in the eNB will be referred to as an eNB processor,
an eNB RF unit, and an eNB memory, respectively.
The UE processor can be configured to operate according to the
present invention, or control the UE RF unit to receive or transmit
signals according to the present invention. The eNB processor can
be configured to operate according to the present invention, or
control the eNB RF unit to receive or transmit signals according to
the present invention.
A processor of a transmitting device generates a MAC PDU according
to present invention, and the processor of the transmitting device
controls the RF unit to transmit the MAC PDU. The processor of the
transmitting device may generate the MAC PDU such that the MAC PDU
includes a MAC CE start indicator according to the present
invention, where the MAC CE start indicator indicates the start
point of the first MAC CE in the MAC PDU. The processor of the
transmitting device may generate the MAC PDU such that the MAC PDU
always includes the MAC CE start indicator even if there is no MAC
CE included in the MAC PDU. The MAC PDU may include zero or more
MAC SDUs and zero or more MAC CEs. The MAC CE start indicator may
indicate the start point by indicating a sum of a total length of
the MAC CEs included in the MAC PDU and a total length of
respective MAC subheaders for the MAC CEs included in the MAC PDU.
The MAC CE start indicator may indicate the start point by
indicating a sum of a total length of the MAC CEs included in the
MAC PDU, a total length of respective MAC subheaders for the MAC
CEs included in the MAC PDU, a length of padding bits included in
the MAC PDU, and a length of a MAC subheader for the padding bits
included in the MAC PDU. The MAC CE start indicator may indicate
wherein the MAC CE start indicator indicates the start point by
indicating a sum of a total length of the MAC SDUs included in the
MAC PDU and a total length of respective MAC subheaders for the MAC
SDUs included in the MAC PDU. The MAC CE start indicator may
indicate the start point by indicating a sum of a total length of
the MAC SDUs included in the MAC PDU, a total length of respective
MAC subheaders for the MAC SDUs included in the MAC PDU, a length
of padding bits included in the MAC PDU, and a length of a MAC
subheader for the padding bits included in the MAC PDU. The
processor of the transmitting device may generate the MAC PDU such
that the zero or more MAC SDUs are placed before the zero or more
MAC CEs in the MAC PDU. The processor of the transmitting device
may generate the MAC PDU such that the MAC CE start indicator is
placed in the beginning or end of the MAC PDU. The MAC PDU may
include no MAC subheader for the MAC CE start indicator. If the
transmitting device is a UE, the processor of the transmitting
device generates the MAC PDU based on a UL grant received from a
receiving side (e.g. BS), and controls the RF unit of the
transmitting device to transmit the MAC PDU using the UL grant. If
the transmitting device is a BS, the processor of the transmitting
device may control the RF unit of the transmitting device to
transmit a DL grant and control the RF unit of the transmitting
device to transmit the MAC PDU using the DL grant.
A processor of a receiving device controls a RF unit of the
receiving device to receive the MAC PDU, and process the MAC PDU
according to the present invention. The processor of the receiving
device may find the location of MAC CE(s) included in the MAC PDU
based on the MAC CE start indicator. If the MAC CE start indicator
is a MAC CE LI of the present invention, the processor of the
receiving device may find the location of the MAC CE(s) in the MAC
PDU by counting the total length of the MAC CEs (and padding bits)
from the end of the MAC PDU. If the MAC CE start indicator is a MAC
CE Pointer of the present invention, the processor of the receiving
device may find the location of MAC CE(s) in the MAC PDU by
counting the offset value from the beginning of the MAC PDU. If the
processor of the receiving device finds the location of MAC CE(s),
i.e., the processor of the receiving device finds where the MAC
CE(s) are placed in the MAC PDU, the processor of the receiving
device may process the MAC CEs prior to processing MAC SDU(s) even
though the MAC CEs are placed after the MAC SDU(s). The processor
of the receiving device may process the MAC CE(s) from the start
point based on the MAC CE start indicator. The processor of the
receiving device may process the MAC PDU from the end of the MAC
PDU toward the start of the MAC PDU. If the receiving device is a
BS, the processor of the receiving device may transmit the RF unit
of the receiving device to transmit a UL grant to a UE and control
the RF unit of the receiving device to receive a MAC PDU using the
UL grant. If the receiving device is a UE, the processor of the
receiving device may control the RF unit of the receiving device to
receive a DL grant and control the RF unit of the receiving device
to a MAC PDU using the DL grant.
As described above, the detailed description of the preferred
embodiments of the present invention has been given to enable those
skilled in the art to implement and practice the invention.
Although the invention has been described with reference to
exemplary embodiments, those skilled in the art will appreciate
that various modifications and variations can be made in the
present invention without departing from the spirit or scope of the
invention described in the appended claims. Accordingly, the
invention should not be limited to the specific embodiments
described herein, but should be accorded the broadest scope
consistent with the principles and novel features disclosed
herein.
INDUSTRIAL APPLICABILITY
The embodiments of the present invention are applicable to a
network node (e.g., BS), a UE, or other devices in a wireless
communication system.
* * * * *